隨著全球市場營業額竄升至數十億，線上拍賣已理所當然成為新的探索市場。在過去幾年間，這種拍賣的市場潛在性迅速增長，並為拍賣的研究和分析提供了新的動力。大量研究和分析顯示，這些線上拍賣的主要困境在於缺乏透明度，以及因集中式的中介與串通投標而增加的交易成本。為了因應這些挑戰，我們提出了一個基於以太坊網絡的完全分散的拍賣平台。這項研究是第一個開發具有交付保證功能的完全分散的英式拍賣平台的研究。這一獨特功能的目標是確保投標人能夠獲得他們在拍賣中得標的產品。此交付保證功能係透過本研究中開發的多重簽名錢包來實現。我們的分散式平台具有額外的安全屬性，例如不可否認性，透明度，以及個人和通用可驗證性。

With an impressive ever-increasing global market turnover amounting to billions, it comes without a surprise that the online auction world has become a breeding ground for new opportunities to explore. The marketability of such auctions has grown rapidly in the last few years, giving a new incentive to the study and analysis of auctions. A lot of research and analysis has shown that the main limitations of these online auctions are the lack of transparency, increased transaction costs due to the centralized intermediary and collusive bidding. In response to these challenges, in this study we present a fully decentralized auction platform based on the Ethereum network. This study is the first to develop a fully decentralized ascending-bid auction (English auction) platform with a delivery guarantee feature. This unique feature has the goal of ensuring bidders that they will receive the product sold on the auctions they won. The delivery guarantee feature is implemented by a multisignature wallet, which is developed in this study. Our decentralized platform comes with additional security properties such as non-repudiation, transparency, individual and universal verifiability.

Table of Contents i
List of Figures iv
1 Introduction 1
1.1 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Contribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.3 Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2 Background 3
2.1 Auctions Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1.1 English Auction . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1.2 Dutch Auction . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1.3 Sealed first-price Auction . . . . . . . . . . . . . . . . . . . . 4
2.1.4 Vickery Auction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2 Common Problems with Online Auctions . . . . . . . . . . . . . . . . 5
2.2.1 Shill Bidding . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2.2 Auction Sniping . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.3 Blockchain Technology . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.4 Blockchain Features . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.4.1 Decentralization . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.4.2 Immutability and Temper detection . . . . . . . . . . . . . . . 8
2.4.3 Relative User Anonymity . . . . . . . . . . . . . . . . . . . . 9
2.4.4 Transparency . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.5 Multisignature Wallet . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.5.1 Defining Multisignatures . . . . . . . . . . . . . . . . . . . . 9
2.5.2 Multisignatures in Cryptocurrencies . . . . . . . . . . . . . . 10
3 Related works 11
4 Design 13
4.1 Design Goal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.2 Auction Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.2.1 Create Auction Protocol . . . . . . . . . . . . . . . . . . . . . 14
4.2.2 Bid Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.2.3 Finalize Auction Protocol . . . . . . . . . . . . . . . . . . . . 16
4.3 Multisignature Wallet . . . . . . . . . . . . . . . . . . . . . . . . . . 16
4.4 Operation Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
4.5 Full Decentralization . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
5 Implementation 19
5.1 System Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
5.2 System Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
5.2.1 Log in Process . . . . . . . . . . . . . . . . . . . . . . . . . . 20
5.2.2 Auction Creation . . . . . . . . . . . . . . . . . . . . . . . . . 22
5.2.3 Bids Management . . . . . . . . . . . . . . . . . . . . . . . . 23
5.2.4 Auction Finalization . . . . . . . . . . . . . . . . . . . . . . . 24
5.2.5 Delivery Guarantee Feature . . . . . . . . . . . . . . . . . . . 24
6 Experiments 26
6.1 Cost Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
6.1.1 Gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
6.1.2 Gas Price . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
6.1.3 Ether Value . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
6.1.4 Cost Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
6.1.5 Comparison With Related Works . . . . . . . . . . . . . . . . 28
7 Conclusion and Future Work 32
7.1 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
7.2 Future Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Bibliography 34

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